diff --git a/examples/lwip/client-coap.c b/examples/lwip/client-coap.c
index 632443e0..6887e097 100644
--- a/examples/lwip/client-coap.c
+++ b/examples/lwip/client-coap.c
@@ -76,7 +76,7 @@ nack_handler(coap_session_t *session COAP_UNUSED,
 
 static int
 resolve_address(const char *host, const char *service, coap_address_t *dst,
-                int scheme_hint_bits) {
+                coap_proto_t *proto, int scheme_hint_bits) {
 
   coap_addr_info_t *addr_info;
   coap_str_const_t str_host;
@@ -92,6 +92,7 @@ resolve_address(const char *host, const char *service, coap_address_t *dst,
   if (addr_info) {
     ret = 1;
     *dst = addr_info->addr;
+    *proto = addr_info->proto;
   }
 
   coap_free_address_info(addr_info);
@@ -118,6 +119,7 @@ client_coap_init(coap_lwip_input_wait_handler_t input_wait, void *input_arg,
   const char *use_psk = "secretPSK";
   const char *use_id = "abc";
   coap_pdu_type_t pdu_type = COAP_MESSAGE_CON;
+  coap_proto_t proto;
 
   /* Initialize libcoap library */
   coap_startup();
@@ -155,17 +157,12 @@ client_coap_init(coap_lwip_input_wait_handler_t input_wait, void *input_arg,
   /* Parse the URI */
   len = coap_split_uri((const unsigned char *)use_uri, strlen(use_uri), &uri);
   LWIP_ASSERT("Failed to parse uri", len == 0);
-  LWIP_ASSERT("Unsupported URI type", uri.scheme == COAP_URI_SCHEME_COAP ||
-              uri.scheme == COAP_URI_SCHEME_COAPS);
-  if (uri.scheme == COAP_URI_SCHEME_COAPS) {
-    LWIP_ASSERT("DTLS not supported", coap_dtls_is_supported());
-  }
 
   snprintf(portbuf, sizeof(portbuf), "%d", uri.port);
   snprintf((char *)buf, sizeof(buf), "%*.*s", (int)uri.host.length,
            (int)uri.host.length, (const char *)uri.host.s);
   /* resolve destination address where server should be sent */
-  len = resolve_address((const char *)buf, portbuf, &dst, 1 << uri.scheme);
+  len = resolve_address((const char *)buf, portbuf, &dst, &proto, 1 << uri.scheme);
   LWIP_ASSERT("Failed to resolve address", len > 0);
 
   main_coap_context = coap_new_context(NULL);
@@ -174,10 +171,8 @@ client_coap_init(coap_lwip_input_wait_handler_t input_wait, void *input_arg,
   coap_context_set_block_mode(main_coap_context, COAP_BLOCK_USE_LIBCOAP);
   coap_lwip_set_input_wait_handler(main_coap_context, input_wait, input_arg);
 
-  if (uri.scheme == COAP_URI_SCHEME_COAP) {
-    session = coap_new_client_session(main_coap_context, NULL, &dst,
-                                      COAP_PROTO_UDP);
-  } else {
+  if (proto == COAP_PROTO_DTLS || proto == COAP_PROTO_TLS ||
+      proto == COAP_PROTO_WSS) {
     static coap_dtls_cpsk_t dtls_psk;
     static char client_sni[256];
 
@@ -197,6 +192,9 @@ client_coap_init(coap_lwip_input_wait_handler_t input_wait, void *input_arg,
 
     session = coap_new_client_session_psk2(main_coap_context, NULL, &dst,
                                            COAP_PROTO_DTLS, &dtls_psk);
+  } else {
+    session = coap_new_client_session(main_coap_context, NULL, &dst,
+                                      proto);
   }
 
   LWIP_ASSERT("Failed to create session", session != NULL);
diff --git a/examples/lwip/config/coap_config.h b/examples/lwip/config/coap_config.h
index ec86c76c..69bf2f0a 100644
--- a/examples/lwip/config/coap_config.h
+++ b/examples/lwip/config/coap_config.h
@@ -33,7 +33,11 @@
 
 #ifndef COAP_DISABLE_TCP
 /* Define to 1 to build without TCP support. */
+#if LWIP_TCP
+#define COAP_DISABLE_TCP 0
+#else /* ! LWIP_TCP */
 #define COAP_DISABLE_TCP 1
+#endif /* ! LWIP_TCP */
 #endif
 
 #ifndef COAP_ASYNC_SUPPORT
@@ -56,11 +60,21 @@
 #define COAP_Q_BLOCK_SUPPORT 0
 #endif
 
+#ifndef PACKAGE_NAME
 #define PACKAGE_NAME "libcoap"
-#define PACKAGE_VERSION "4.3.4"
-#define PACKAGE_STRING "libcoap 4.3.4"
+#endif /* PACKAGE_NAME */
 
+#ifndef PACKAGE_VERSION
+#define PACKAGE_VERSION "4.3.4"
+#endif /* PACKAGE_VERSION */
+
+#ifndef PACKAGE_STRING
+#define PACKAGE_STRING "libcoap 4.3.4"
+#endif /* PACKAGE_STRING */
+
+#ifndef assert
 #define assert(x) LWIP_ASSERT("CoAP assert failed", x)
+#endif /* assert */
 
 /* it's just provided by libc. i hope we don't get too many of those, as
  * actually we'd need autotools again to find out what environment we're
diff --git a/examples/lwip/config/coap_config.h.in b/examples/lwip/config/coap_config.h.in
index 80899659..4549fcb4 100644
--- a/examples/lwip/config/coap_config.h.in
+++ b/examples/lwip/config/coap_config.h.in
@@ -33,7 +33,11 @@
 
 #ifndef COAP_DISABLE_TCP
 /* Define to 1 to build without TCP support. */
+#if LWIP_TCP
+#define COAP_DISABLE_TCP 0
+#else /* ! LWIP_TCP */
 #define COAP_DISABLE_TCP 1
+#endif /* ! LWIP_TCP */
 #endif
 
 #ifndef COAP_ASYNC_SUPPORT
@@ -56,11 +60,21 @@
 #define COAP_Q_BLOCK_SUPPORT 0
 #endif
 
+#ifndef PACKAGE_NAME
 #define PACKAGE_NAME "@PACKAGE_NAME@"
-#define PACKAGE_VERSION "@PACKAGE_VERSION@"
-#define PACKAGE_STRING "@PACKAGE_STRING@"
+#endif /* PACKAGE_NAME */
 
+#ifndef PACKAGE_VERSION
+#define PACKAGE_VERSION "@PACKAGE_VERSION@"
+#endif /* PACKAGE_VERSION */
+
+#ifndef PACKAGE_STRING
+#define PACKAGE_STRING "@PACKAGE_STRING@"
+#endif /* PACKAGE_STRING */
+
+#ifndef assert
 #define assert(x) LWIP_ASSERT("CoAP assert failed", x)
+#endif /* assert */
 
 /* it's just provided by libc. i hope we don't get too many of those, as
  * actually we'd need autotools again to find out what environment we're
diff --git a/examples/lwip/config/lwipopts.h b/examples/lwip/config/lwipopts.h
index 4543c7eb..929c40dc 100644
--- a/examples/lwip/config/lwipopts.h
+++ b/examples/lwip/config/lwipopts.h
@@ -23,6 +23,9 @@
 #define LWIP_IPV6_MLD                   0
 #define LWIP_ICMP6                 (LWIP_IPV6==1)
 
+/* Set to 1 if TCP support is required */
+#define LWIP_TCP                        0
+
 #ifndef LWIP_RAND
 #define LWIP_RAND() ((u32_t)rand())
 #endif
@@ -36,6 +39,8 @@
 #define UNLOCK_TCPIP_CORE()
 #endif
 
+#define MEMP_NUM_SYS_TIMEOUT    10
+
 #define MEMP_USE_CUSTOM_POOLS 1
 #define MEM_SIZE (4 * 1024)
 /* Support a 1500 MTU packet */
diff --git a/examples/lwip/config/lwippools.h b/examples/lwip/config/lwippools.h
index 6a8409ed..eef70b75 100644
--- a/examples/lwip/config/lwippools.h
+++ b/examples/lwip/config/lwippools.h
@@ -43,11 +43,19 @@ typedef struct l_coap_tiny_context_t {
 #endif
 
 #ifndef MEMP_NUM_COAPENDPOINT
+#if COAP_DISABLE_TCP
 #ifdef COAP_WITH_LIBTINYDTLS
 #define MEMP_NUM_COAPENDPOINT 2
 #else /* ! COAP_WITH_LIBTINYDTLS */
 #define MEMP_NUM_COAPENDPOINT 1
 #endif /* ! COAP_WITH_LIBTINYDTLS */
+#else /* ! COAP_DISABLE_TCP */
+#ifdef COAP_WITH_LIBTINYDTLS
+#define MEMP_NUM_COAPENDPOINT 4
+#else /* ! COAP_WITH_LIBTINYDTLS */
+#define MEMP_NUM_COAPENDPOINT 2
+#endif /* ! COAP_WITH_LIBTINYDTLS */
+#endif /* ! COAP_DISABLE_TCP */
 #endif
 
 /* 1 is sufficient as this is very short-lived */
@@ -92,7 +100,11 @@ typedef struct l_coap_tiny_context_t {
 #endif
 
 #ifndef MEMP_LEN_COAPSTRING
+#ifdef COAP_WITH_LIBTINYDTLS
+#define MEMP_LEN_COAPSTRING 120
+#else /* COAP_WITH_TINYDTLS */
 #define MEMP_LEN_COAPSTRING 40
+#endif /* COAP_WITH_TINYDTLS */
 #endif
 
 #ifndef MEMP_NUM_COAPCACHE_KEYS
diff --git a/include/coap3/coap_io_internal.h b/include/coap3/coap_io_internal.h
index a9506d27..5d686bd7 100644
--- a/include/coap3/coap_io_internal.h
+++ b/include/coap3/coap_io_internal.h
@@ -33,7 +33,12 @@ struct uip_udp_conn;
 
 struct coap_socket_t {
 #if defined(WITH_LWIP)
-  struct udp_pcb *pcb;
+  struct pbuf *p;
+  struct udp_pcb *udp_pcb;
+#if ! COAP_DISABLE_TCP
+  struct tcp_pcb *tcp_pcb;
+#endif /* ! COAP_DISABLE_TCP */
+
 #elif defined(WITH_CONTIKI)
   struct uip_udp_conn *udp_conn;
   coap_context_t *context;
diff --git a/include/coap3/coap_mem.h b/include/coap3/coap_mem.h
index ad6a464a..bdc22f61 100644
--- a/include/coap3/coap_mem.h
+++ b/include/coap3/coap_mem.h
@@ -143,13 +143,26 @@ coap_free(void *object) {
 COAP_STATIC_INLINE void
 coap_memory_init(void) {}
 
+#if MEMP_STATS
+COAP_STATIC_INLINE void *
+coap_malloc_error(uint16_t *err) {
+  (*err)++;
+  return NULL;
+}
+#endif /* MEMP_STATS */
 /* It would be nice to check that size equals the size given at the memp
  * declaration, but i currently don't see a standard way to check that without
  * sourcing the custom memp pools and becoming dependent of its syntax
  */
+#if MEMP_STATS
+#define coap_malloc_type(type, asize) \
+  (((asize) <= memp_pools[MEMP_ ## type]->size) ? \
+   memp_malloc(MEMP_ ## type) : coap_malloc_error(&memp_pools[MEMP_ ## type]->stats->err))
+#else /* ! MEMP_STATS */
 #define coap_malloc_type(type, asize) \
   (((asize) <= memp_pools[MEMP_ ## type]->size) ? \
    memp_malloc(MEMP_ ## type) : NULL)
+#endif /* ! MEMP_STATS */
 #define coap_free_type(type, p) memp_free(MEMP_ ## type, p)
 
 /* As these are fixed size, return value if already defined */
diff --git a/include/coap3/coap_netif_internal.h b/include/coap3/coap_netif_internal.h
index 1196e73e..71c44513 100644
--- a/include/coap3/coap_netif_internal.h
+++ b/include/coap3/coap_netif_internal.h
@@ -128,10 +128,12 @@ int coap_netif_strm_listen(coap_endpoint_t *endpoint,
  *
  * @param endpoint Endpoint to to do the accept on.
  * @param session  Session to to do the accept update on.
+ * @param extra    Available for use by any underlying network stack.
  *
  * @return                 @c 1 OK, 0 on failure.
  */
-int coap_netif_strm_accept(coap_endpoint_t *endpoint, coap_session_t *session);
+int coap_netif_strm_accept(coap_endpoint_t *endpoint, coap_session_t *session,
+                           void *extra);
 
 /**
  * Layer function interface for Netif stream connect (tcp).
diff --git a/include/coap3/coap_session_internal.h b/include/coap3/coap_session_internal.h
index b0a6710e..b3698bd3 100644
--- a/include/coap3/coap_session_internal.h
+++ b/include/coap3/coap_session_internal.h
@@ -309,14 +309,14 @@ int coap_session_refresh_psk_identity(coap_session_t *session,
  * Creates a new server session for the specified endpoint.
  * @param ctx The CoAP context.
  * @param ep An endpoint where an incoming connection request is pending.
+ * @param extra Available for use by any underlying network stack.
  *
  * @return A new CoAP session or NULL if failed. Call coap_session_release to
  * add to unused queue.
  */
-coap_session_t *coap_new_server_session(
-    coap_context_t *ctx,
-    coap_endpoint_t *ep
-);
+coap_session_t *coap_new_server_session(coap_context_t *ctx,
+                                        coap_endpoint_t *ep,
+                                        void *extra);
 #endif /* COAP_SERVER_SUPPORT */
 
 /**
@@ -384,6 +384,10 @@ coap_session_t *coap_session_new_dtls_session(coap_session_t *session,
 void coap_session_free(coap_session_t *session);
 void coap_session_mfree(coap_session_t *session);
 
+void coap_read_session(coap_context_t *ctx, coap_session_t *session, coap_tick_t now);
+
+void coap_connect_session(coap_session_t *session, coap_tick_t now);
+
 #define COAP_SESSION_REF(s) ((s)->ref
 
 /* RFC7252 */
diff --git a/include/coap3/coap_tcp_internal.h b/include/coap3/coap_tcp_internal.h
index e14a927a..f57d14b6 100644
--- a/include/coap3/coap_tcp_internal.h
+++ b/include/coap3/coap_tcp_internal.h
@@ -93,13 +93,15 @@ int coap_socket_bind_tcp(coap_socket_t *sock,
  *                   session information
  * @param local_addr Filled in with the local address
  * @param remote_addr Filled in with the remote address
+ * @param extra Available for use by any underlying network stack.
  *
  * @return @c 1 if succesful, @c 0 if failure of some sort
 */
 int coap_socket_accept_tcp(coap_socket_t *server,
                            coap_socket_t *new_client,
                            coap_address_t *local_addr,
-                           coap_address_t *remote_addr);
+                           coap_address_t *remote_addr,
+                           void *extra);
 
 #endif /* !COAP_DISABLE_TCP */
 
diff --git a/src/coap_io_lwip.c b/src/coap_io_lwip.c
index 636daa39..6e4de8a6 100644
--- a/src/coap_io_lwip.c
+++ b/src/coap_io_lwip.c
@@ -202,7 +202,7 @@ coap_free_packet(coap_packet_t *packet) {
   coap_free_type(COAP_PACKET, packet);
 }
 
-/** Callback from lwIP when a package was received for a server.
+/** Callback from lwIP when a UDP packet was received for a server.
  *
  * The current implementation deals this to coap_dispatch immediately, but
  * other mechanisms (as storing the package in a queue and later fetching it
@@ -211,8 +211,8 @@ coap_free_packet(coap_packet_t *packet) {
  * It handles everything coap_io_do_io does on other implementations.
  */
 static void
-coap_recvs(void *arg, struct udp_pcb *upcb, struct pbuf *p,
-           const ip_addr_t *addr, u16_t port) {
+coap_udp_recvs(void *arg, struct udp_pcb *upcb, struct pbuf *p,
+               const ip_addr_t *addr, u16_t port) {
   coap_endpoint_t *ep = (coap_endpoint_t *)arg;
   coap_pdu_t *pdu = NULL;
   coap_session_t *session = NULL;
@@ -304,7 +304,7 @@ coap_socket_send_pdu(coap_socket_t *sock, coap_session_t *session,
     pbuf = pbuf_clone(PBUF_TRANSPORT, PBUF_RAM, pdu->pbuf);
     if (pbuf == NULL)
       return -1;
-    err = udp_sendto(sock->pcb, pbuf, &session->addr_info.remote.addr,
+    err = udp_sendto(sock->udp_pcb, pbuf, &session->addr_info.remote.addr,
                      session->addr_info.remote.port);
     pbuf_free(pbuf);
     if (err < 0)
@@ -332,7 +332,7 @@ coap_socket_send(coap_socket_t *sock, const coap_session_t *session,
 
     LOCK_TCPIP_CORE();
 
-    err = udp_sendto(sock->pcb, pbuf, &session->addr_info.remote.addr,
+    err = udp_sendto(sock->udp_pcb, pbuf, &session->addr_info.remote.addr,
                      session->addr_info.remote.port);
 
     UNLOCK_TCPIP_CORE();
@@ -352,19 +352,19 @@ coap_socket_bind_udp(coap_socket_t *sock,
   int err;
   coap_address_t l_listen = *listen_addr;
 
-  sock->pcb = udp_new_ip_type(IPADDR_TYPE_ANY);
-  if (sock->pcb == NULL)
+  sock->udp_pcb = udp_new_ip_type(IPADDR_TYPE_ANY);
+  if (sock->udp_pcb == NULL)
     return 0;
 
 #if LWIP_IPV6 && LWIP_IPV4
   if (l_listen.addr.type == IPADDR_TYPE_V6)
     l_listen.addr.type = IPADDR_TYPE_ANY;
 #endif /* LWIP_IPV6 && LWIP_IPV4 */
-  udp_recv(sock->pcb, coap_recvs, (void *)sock->endpoint);
-  err = udp_bind(sock->pcb, &l_listen.addr, l_listen.port);
+  udp_recv(sock->udp_pcb, coap_udp_recvs, (void *)sock->endpoint);
+  err = udp_bind(sock->udp_pcb, &l_listen.addr, l_listen.port);
   if (err) {
-    udp_remove(sock->pcb);
-    sock->pcb = NULL;
+    udp_remove(sock->udp_pcb);
+    sock->udp_pcb = NULL;
   }
   *bound_addr = l_listen;
   return err ? 0 : 1;
@@ -413,9 +413,9 @@ coap_socket_connect_udp(coap_socket_t *sock,
   pcb->local_ip.type = pcb->remote_ip.type;
 #endif /* LWIP_IPV6 && LWIP_IPV4 */
 
-  sock->pcb = pcb;
+  sock->udp_pcb = pcb;
 
-  udp_recv(sock->pcb, coap_recvc, (void *)sock->session);
+  udp_recv(sock->udp_pcb, coap_recvc, (void *)sock->session);
 
   UNLOCK_TCPIP_CORE();
 
@@ -431,6 +431,77 @@ err_unlock:
 #endif /* ! COAP_CLIENT_SUPPORT */
 
 #if ! COAP_DISABLE_TCP
+
+#include <lwip/tcp.h>
+
+static void
+do_tcp_err(void *arg, err_t err) {
+  coap_session_t *session = (coap_session_t *)arg;
+
+  (void)err;
+
+  coap_handle_event(session->context, COAP_EVENT_TCP_FAILED, session);
+  /*
+   * as per tcp_err() documentation, the corresponding pcb is already freed
+   * when this callback is called.  So, stop a double free when
+   * coap_session_disconnected() eventually coap_socket_close() is called.
+   */
+  session->sock.tcp_pcb = NULL;
+  coap_session_disconnected(session, COAP_NACK_NOT_DELIVERABLE);
+}
+
+/** Callback from lwIP when a TCP packet is received.
+ *
+ * The current implementation invokes coap_read_session() to do the bulk of the
+ * work.
+ */
+static err_t
+coap_tcp_recv(void *arg, struct tcp_pcb *tpcb, struct pbuf *p, err_t err) {
+  coap_session_t *session = (coap_session_t *)arg;
+  coap_socket_t *sock = &session->sock;
+  coap_tick_t now;
+
+  (void)tpcb;
+  if (p == NULL) {
+    /* remote host closed connection */
+    tcp_arg(sock->tcp_pcb, NULL);
+    tcp_recv(sock->tcp_pcb, NULL);
+    tcp_close(sock->tcp_pcb);
+    sock->tcp_pcb = NULL;
+    coap_session_disconnected(session, COAP_NACK_NOT_DELIVERABLE);
+    return ERR_OK;
+  } else if (err != ERR_OK) {
+    /* cleanup, for unknown reason */
+    if (p != NULL) {
+      pbuf_free(p);
+    }
+    return err;
+  }
+
+  sock->p = p;
+  coap_ticks(&now);
+  coap_read_session(session->context, session, now);
+  return ERR_OK;
+}
+
+#if COAP_CLIENT_SUPPORT
+
+static err_t
+do_tcp_connected(void *arg, struct tcp_pcb *tpcb, err_t err) {
+  coap_session_t *session = (coap_session_t *)arg;
+  coap_tick_t now;
+
+  if (err)
+    return err;
+  session->sock.flags |= COAP_SOCKET_CONNECTED;
+  session->addr_info.local.addr = tpcb->local_ip;
+  session->addr_info.local.port = tpcb->local_port;
+  tcp_recv(tpcb, coap_tcp_recv);
+  coap_ticks(&now);
+  coap_connect_session(session, now);
+  return ERR_OK;
+}
+
 int
 coap_socket_connect_tcp1(coap_socket_t *sock,
                          const coap_address_t *local_if,
@@ -438,13 +509,45 @@ coap_socket_connect_tcp1(coap_socket_t *sock,
                          int default_port,
                          coap_address_t *local_addr,
                          coap_address_t *remote_addr) {
-  (void)sock;
-  (void)local_if;
-  (void)server;
-  (void)default_port;
+  coap_address_t connect_addr;
+  err_t err;
+
   (void)local_addr;
   (void)remote_addr;
-  return 0;
+
+  sock->flags &= ~(COAP_SOCKET_WANT_CONNECT | COAP_SOCKET_CONNECTED);
+
+  sock->tcp_pcb = tcp_new_ip_type(IPADDR_TYPE_ANY);
+  if (sock->tcp_pcb == NULL)
+    return 0;
+
+  tcp_arg(sock->tcp_pcb, sock->session);
+  tcp_recv(sock->tcp_pcb, coap_tcp_recv);
+  tcp_err(sock->tcp_pcb, do_tcp_err);
+  if (local_if) {
+    coap_address_t l_local_if = *local_if;
+#if LWIP_IPV6 && LWIP_IPV4
+    if (l_local_if.addr.type == IPADDR_TYPE_V6)
+      l_local_if.addr.type = IPADDR_TYPE_ANY;
+#endif /* LWIP_IPV6 && LWIP_IPV4 */
+    err = tcp_bind(sock->tcp_pcb, &l_local_if.addr, l_local_if.port);
+    if (err != ERR_OK) {
+      tcp_arg(sock->tcp_pcb, NULL);
+      tcp_recv(sock->tcp_pcb, NULL);
+      tcp_close(sock->tcp_pcb);
+      sock->tcp_pcb = NULL;
+      return 0;
+    }
+  }
+  coap_address_copy(&connect_addr, server);
+  if (connect_addr.port == 0)
+    connect_addr.port = htons(default_port);
+
+  err = tcp_connect(sock->tcp_pcb, &connect_addr.addr, connect_addr.port,
+                    do_tcp_connected);
+  if (err == ERR_OK)
+    sock->flags |= COAP_SOCKET_WANT_CONNECT | COAP_SOCKET_CONNECTED;
+  return err ? 0 : 1;
 }
 
 int
@@ -454,55 +557,174 @@ coap_socket_connect_tcp2(coap_socket_t *sock,
   (void)sock;
   (void)local_addr;
   (void)remote_addr;
-  return 0;
+
+  sock->flags &= ~(COAP_SOCKET_WANT_CONNECT | COAP_SOCKET_CAN_CONNECT);
+  return 1;
+}
+#endif /* COAP_CLIENT_SUPPORT */
+
+#if COAP_SERVER_SUPPORT
+
+static err_t
+do_tcp_accept(void *arg, struct tcp_pcb *newpcb, err_t err) {
+  coap_endpoint_t *endpoint = arg;
+  coap_session_t *session;
+  coap_tick_t now;
+  err_t ret_err = ERR_OK;
+
+  if ((err != ERR_OK) || (newpcb == NULL)) {
+    return ERR_VAL;
+  }
+  coap_ticks(&now);
+
+  session = coap_new_server_session(endpoint->context, endpoint, newpcb);
+
+  if (session) {
+    session->sock.tcp_pcb = newpcb;
+    session->last_rx_tx = now;
+    tcp_arg(newpcb, session);
+    tcp_setprio(newpcb, TCP_PRIO_MIN);
+    tcp_recv(newpcb, coap_tcp_recv);
+    tcp_err(newpcb, do_tcp_err);
+  } else {
+    ret_err = ERR_MEM;
+  }
+  return ret_err;
 }
 
 int
 coap_socket_bind_tcp(coap_socket_t *sock,
                      const coap_address_t *listen_addr,
                      coap_address_t *bound_addr) {
-  (void)sock;
-  (void)listen_addr;
-  (void)bound_addr;
-  return 0;
+  int err;
+  coap_address_t l_listen = *listen_addr;
+  struct tcp_pcb *tcp_pcb;
+
+  sock->tcp_pcb = tcp_new_ip_type(IPADDR_TYPE_ANY);
+  if (sock->tcp_pcb == NULL)
+    return 0;
+
+#if LWIP_IPV6 && LWIP_IPV4
+  if (l_listen.addr.type == IPADDR_TYPE_V6)
+    l_listen.addr.type = IPADDR_TYPE_ANY;
+#endif /* LWIP_IPV6 && LWIP_IPV4 */
+  tcp_arg(sock->tcp_pcb, sock->endpoint);
+  err = tcp_bind(sock->tcp_pcb, &l_listen.addr, l_listen.port);
+  if (err != ERR_OK) {
+    tcp_arg(sock->tcp_pcb, NULL);
+    tcp_recv(sock->tcp_pcb, NULL);
+    tcp_close(sock->tcp_pcb);
+    sock->tcp_pcb = NULL;
+    return 0;
+  } else {
+    tcp_pcb = tcp_listen(sock->tcp_pcb);
+    if (tcp_pcb) {
+      sock->tcp_pcb = tcp_pcb;
+      tcp_accept(sock->tcp_pcb, do_tcp_accept);
+    } else {
+      tcp_arg(sock->tcp_pcb, NULL);
+      tcp_recv(sock->tcp_pcb, NULL);
+      tcp_close(sock->tcp_pcb);
+      sock->tcp_pcb = NULL;
+      return 0;
+    }
+  }
+  *bound_addr = l_listen;
+  return err ? 0 : 1;
 }
 
 int
 coap_socket_accept_tcp(coap_socket_t *server,
                        coap_socket_t *new_client,
                        coap_address_t *local_addr,
-                       coap_address_t *remote_addr) {
+                       coap_address_t *remote_addr,
+                       void *extra) {
+  struct tcp_pcb *tcp_pcb = (struct tcp_pcb *)extra;
+
   (void)server;
-  (void)new_client;
-  (void)local_addr;
-  (void)remote_addr;
+
+  new_client->tcp_pcb = tcp_pcb;
+  local_addr->addr = tcp_pcb->local_ip;
+  local_addr->port = tcp_pcb->local_port;
+  remote_addr->addr = tcp_pcb->remote_ip;
+  remote_addr->port = tcp_pcb->remote_port;
+  return 1;
+}
+#endif /* COAP_SERVER_SUPPORT */
+
+/*
+ * strm
+ * return +ve Number of bytes written.
+ *         -1 Error error in errno).
+ */
+ssize_t
+coap_socket_write(coap_socket_t *sock, const uint8_t *data, size_t data_len) {
+  struct pbuf *pbuf;
+  int err;
+
+  pbuf = pbuf_alloc(PBUF_TRANSPORT, data_len, PBUF_RAM);
+  if (pbuf == NULL)
+    return -1;
+  memcpy(pbuf->payload, data, data_len);
+
+  LOCK_TCPIP_CORE();
+
+  err = tcp_write(sock->tcp_pcb, pbuf->payload, pbuf->len, 1);
+
+  UNLOCK_TCPIP_CORE();
+
+  pbuf_free(pbuf);
+  if (err < 0)
+    return -1;
+  return data_len;
+}
+
+/*
+ * strm
+ * return >=0 Number of bytes read.
+ *         -1 Error error in errno).
+ */
+ssize_t
+coap_socket_read(coap_socket_t *sock, uint8_t *data, size_t data_len) {
+  if (sock->p) {
+    if (data_len < sock->p->len) {
+      uint8_t *ptr = (uint8_t *)sock->p->payload;
+
+      /* Handle partial read of data request */
+      memcpy(data, sock->p->payload, data_len);
+      sock->p->payload = &ptr[data_len];
+      sock->p->len -= data_len;
+      return data_len;
+    } else {
+      data_len = sock->p->len;
+      memcpy(data, sock->p->payload, sock->p->len);
+      pbuf_free(sock->p);
+      sock->p = NULL;
+      return data_len;
+    }
+  }
   return 0;
 }
 #endif /* !COAP_DISABLE_TCP */
 
-ssize_t
-coap_socket_write(coap_socket_t *sock, const uint8_t *data, size_t data_len) {
-  (void)sock;
-  (void)data;
-  (void)data_len;
-  return -1;
-}
-
-ssize_t
-coap_socket_read(coap_socket_t *sock, uint8_t *data, size_t data_len) {
-  (void)sock;
-  (void)data;
-  (void)data_len;
-  return -1;
-}
-
 void
 coap_socket_close(coap_socket_t *sock) {
-  if (sock->pcb) {
+  if (sock->udp_pcb) {
     LOCK_TCPIP_CORE();
-    udp_remove(sock->pcb);
+    udp_remove(sock->udp_pcb);
     UNLOCK_TCPIP_CORE();
+    sock->udp_pcb = NULL;
   }
-  sock->pcb = NULL;
+#if ! COAP_DISABLE_TCP
+  if (sock->tcp_pcb) {
+    tcp_arg(sock->tcp_pcb, NULL);
+#if COAP_SERVER_SUPPORT
+    if (!sock->endpoint)
+#endif /* COAP_SERVER_SUPPORT */
+      tcp_recv(sock->tcp_pcb, NULL);
+    tcp_close(sock->tcp_pcb);
+    sock->tcp_pcb = NULL;
+  }
+#endif /* !COAP_DISABLE_TCP */
   return;
 }
diff --git a/src/coap_net.c b/src/coap_net.c
index 17de6105..b97be8db 100644
--- a/src/coap_net.c
+++ b/src/coap_net.c
@@ -1761,7 +1761,7 @@ coap_handle_dgram_for_proto(coap_context_t *ctx, coap_session_t *session, coap_p
 }
 
 #if COAP_CLIENT_SUPPORT
-static void
+void
 coap_connect_session(coap_session_t *session, coap_tick_t now) {
 #if COAP_DISABLE_TCP
   (void)now;
@@ -1808,7 +1808,7 @@ coap_write_session(coap_context_t *ctx, coap_session_t *session, coap_tick_t now
   }
 }
 
-static void
+void
 coap_read_session(coap_context_t *ctx, coap_session_t *session, coap_tick_t now) {
 #if COAP_CONSTRAINED_STACK
   /* payload and packet protected by mutex m_read_session */
@@ -2061,8 +2061,8 @@ coap_write_endpoint(coap_context_t *ctx, coap_endpoint_t *endpoint, coap_tick_t
 #if !COAP_DISABLE_TCP
 static int
 coap_accept_endpoint(coap_context_t *ctx, coap_endpoint_t *endpoint,
-                     coap_tick_t now) {
-  coap_session_t *session = coap_new_server_session(ctx, endpoint);
+                     coap_tick_t now, void *extra) {
+  coap_session_t *session = coap_new_server_session(ctx, endpoint, extra);
   if (session)
     session->last_rx_tx = now;
   return session != NULL;
@@ -2088,7 +2088,7 @@ coap_io_do_io(coap_context_t *ctx, coap_tick_t now) {
       coap_write_endpoint(ctx, ep, now);
 #if !COAP_DISABLE_TCP
     if ((ep->sock.flags & COAP_SOCKET_CAN_ACCEPT) != 0)
-      coap_accept_endpoint(ctx, ep, now);
+      coap_accept_endpoint(ctx, ep, now, NULL);
 #endif /* !COAP_DISABLE_TCP */
     SESSIONS_ITER_SAFE(ep->sessions, s, rtmp) {
       /* Make sure the session object is not deleted in one of the callbacks  */
@@ -2168,7 +2168,7 @@ coap_io_do_epoll(coap_context_t *ctx, struct epoll_event *events, size_t nevents
         if ((sock->flags & COAP_SOCKET_WANT_ACCEPT) &&
             (events[j].events & EPOLLIN)) {
           sock->flags |= COAP_SOCKET_CAN_ACCEPT;
-          coap_accept_endpoint(endpoint->context, endpoint, now);
+          coap_accept_endpoint(endpoint->context, endpoint, now, NULL);
         }
 #endif /* !COAP_DISABLE_TCP */
 
diff --git a/src/coap_netif.c b/src/coap_netif.c
index 2df5f66e..13442aa6 100644
--- a/src/coap_netif.c
+++ b/src/coap_netif.c
@@ -167,10 +167,10 @@ coap_netif_strm_listen(coap_endpoint_t *endpoint,
 }
 
 int
-coap_netif_strm_accept(coap_endpoint_t *endpoint, coap_session_t *session) {
+coap_netif_strm_accept(coap_endpoint_t *endpoint, coap_session_t *session, void *extra) {
   if (!coap_socket_accept_tcp(&endpoint->sock, &session->sock,
                               &session->addr_info.local,
-                              &session->addr_info.remote)) {
+                              &session->addr_info.remote, extra)) {
     return 0;
   }
   session->sock.flags |= COAP_SOCKET_NOT_EMPTY | COAP_SOCKET_CONNECTED |
diff --git a/src/coap_session.c b/src/coap_session.c
index 682729ca..2d5a0cd7 100644
--- a/src/coap_session.c
+++ b/src/coap_session.c
@@ -492,7 +492,8 @@ coap_session_mfree(coap_session_t *session) {
 
   if (session->partial_pdu)
     coap_delete_pdu(session->partial_pdu);
-  session->sock.lfunc[COAP_LAYER_SESSION].l_close(session);
+  if (session->sock.lfunc[COAP_LAYER_SESSION].l_close)
+    session->sock.lfunc[COAP_LAYER_SESSION].l_close(session);
   if (session->psk_identity)
     coap_delete_bin_const(session->psk_identity);
   if (session->psk_key)
@@ -1529,7 +1530,7 @@ coap_new_client_session_pki(coap_context_t *ctx,
 #if COAP_SERVER_SUPPORT
 #if !COAP_DISABLE_TCP
 coap_session_t *
-coap_new_server_session(coap_context_t *ctx, coap_endpoint_t *ep) {
+coap_new_server_session(coap_context_t *ctx, coap_endpoint_t *ep, void *extra) {
   coap_session_t *session;
   session = coap_make_session(ep->proto, COAP_SESSION_TYPE_SERVER,
                               NULL, NULL, NULL, 0, ctx, ep);
@@ -1537,7 +1538,7 @@ coap_new_server_session(coap_context_t *ctx, coap_endpoint_t *ep) {
     goto error;
 
   memcpy(session->sock.lfunc, ep->sock.lfunc, sizeof(session->sock.lfunc));
-  if (!coap_netif_strm_accept(ep, session))
+  if (!coap_netif_strm_accept(ep, session, extra))
     goto error;
 
   coap_make_addr_hash(&session->addr_hash, session->proto, &session->addr_info);
diff --git a/src/coap_tcp.c b/src/coap_tcp.c
index 124a927a..f84f84a5 100644
--- a/src/coap_tcp.c
+++ b/src/coap_tcp.c
@@ -38,7 +38,7 @@ coap_tcp_is_supported(void) {
   return !COAP_DISABLE_TCP;
 }
 
-#if !COAP_DISABLE_TCP
+#if !COAP_DISABLE_TCP && !defined(WITH_LWIP)
 int
 coap_socket_connect_tcp1(coap_socket_t *sock,
                          const coap_address_t *local_if,
@@ -176,12 +176,12 @@ coap_socket_connect_tcp2(coap_socket_t *sock,
 
   if (getsockopt(sock->fd, SOL_SOCKET, SO_ERROR, OPTVAL_GT(&error),
                  &optlen) == COAP_SOCKET_ERROR) {
-    coap_log_warn("coap_socket_finish_connect_tcp: getsockopt: %s\n",
+    coap_log_warn("coap_socket_connect_tcp2: getsockopt: %s\n",
                   coap_socket_strerror());
   }
 
   if (error) {
-    coap_log_warn("coap_socket_finish_connect_tcp: connect failed: %s\n",
+    coap_log_warn("coap_socket_connect_tcp2: connect failed: %s\n",
                   coap_socket_format_errno(error));
     coap_socket_close(sock);
     return 0;
@@ -299,7 +299,8 @@ int
 coap_socket_accept_tcp(coap_socket_t *server,
                        coap_socket_t *new_client,
                        coap_address_t *local_addr,
-                       coap_address_t *remote_addr) {
+                       coap_address_t *remote_addr,
+                       void *extra) {
 #ifndef RIOT_VERSION
 #ifdef _WIN32
   u_long u_on = 1;
@@ -307,6 +308,7 @@ coap_socket_accept_tcp(coap_socket_t *server,
   int on = 1;
 #endif
 #endif /* RIOT_VERSION */
+  (void)extra;
 
   server->flags &= ~COAP_SOCKET_CAN_ACCEPT;